This invention relates to the recovery of magnetic recorded binary data, and more particularly to a phase-locked loop for tracking recorded binary data as it is read to provide clock pulses for use in data recovery.
Phase-locked loops (PLL's) have been employed in the past to track and phase lock onto data from magnetically recorded medium. The output of the PLL is then used as a clock for data recovery. However, in each case the PLL has evidently been designed for the particular application, i.e., for the data rate of the magnetic recording system. For example, in a cassette magnetic tape system capable of recording with a bit density of 800 bits per inch, some systems will operate at 3 IPS while others will operate at 6 IPS. A PLL designed to operate optimally at 2400 bits per second will not track well at 4800 bits per second. What is required is a low cost PLL with versatility for adaptability to different uses over a wide range of operating frequencies, such as 1KHz to 10 or 20 MHz.